Fracturing pump assembly

ABSTRACT

An improved fracturing pump is provided. The pump is reconfigurable on site. Internal components of the pump may be varied to meet the requirements of a specific operation. The reconfiguration gives the user the ability to increase or decrease the horsepower of the pump. A closed loop oil feed system provides constant and reliable lubrication even under heavy loads. The sealing system is enhanced to reduce leaks and thermal stresses. The pump also has an improved frame and chassis to reduce NVH and enhance reliability.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to pumps, and in particular, to an improved fracturing pump assembly.

2. Description of the Prior Art

Drilling and production systems are often employed to access and extract hydrocarbons from subterranean formations. These systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead assembly mounted on a well through which the resource is accessed or extracted. These wellhead assemblies may include a wide variety of components, such as various casings, valves, pumps, fluid conduits, and the like, that control drilling or extraction operations.

Drilling and production operations, such as fracking, employ fluids referred to as fracturing or drilling fluids to provide lubrication and cooling of the drill bit, clear away cuttings, and maintain desired hydrostatic pressure during operations. Fracturing can include all types of water-based, oil-based, or synthetic-based drilling fluids. Fracturing pumps can be used to move large quantities of fracturing fluid from surface tanks, down thousands of feet of drill pipe, out of nozzles in the bit, back up the annulus, and back to the tanks. Operations come to a halt if the fracturing pumps fail, and thus, reliability under harsh conditions, using all types of abrasive fluids, is of utmost commercial interest. Also, portability of these pumps is an issue, so having a versatile pump which can meet the needs of virtually any situation would be desirable.

An improved fracturing pump is provided. The pump is reconfigurable on site. Internal components of the pump may be varied to meet the requirements of a specific operation. The reconfiguration gives the user the ability to increase or decrease the horsepower of the pump. A closed loop oil feed system provides constant and reliable lubrication even under heavy loads. The sealing system is enhanced to reduce leaks and thermal stresses. The pump also has an improved frame and chassis to reduce NVH and enhance reliability.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide an improved fracturing pump assembly.

It is another object of the invention to provide a fracturing pump assembly with interchangeable parts.

It is another object of the invention to provide a fracturing pump assembly with a variable power output.

It is another object of the invention to provide a fracturing pump assembly with an improved crosshead design.

It is another object of the invention to provide a fracturing pump assembly having a fluid end with a 45 degree valve seat.

It is another object of the invention to provide a fracturing pump assembly having an improved frame which utilizes partition support.

It is another object of the invention to provide a fracturing pump assembly where the pump frame is integrated into the skid chassis.

It is another object of the invention to provide a fracturing pump assembly with a closed loop lubricating system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 generally depicts a wellsite system, in accordance with one or more implementations described herein.

FIG. 2 shows a side cutaway view of a prior art pump.

FIG. 3 shows a perspective view, partly in section, of a first embodiment of the fracturing pump assembly of the invention.

FIG. 4 shows a perspective view of a frame and chassis arrangement for the fracturing pump assembly of FIG. 3.

FIG. 5 shows a perspective view of the pump of FIG. 4.

FIG. 6 shows a plan view of the crankshaft bearing.

FIG. 7 is a diagram of the closed loop oil feed system of the invention.

FIG. 8 is a system flowchart depicting operational aspects of the assembly of the invention.

FIG. 9 is a diagrammatic illustration of the forces acting on the assembly of the invention.

FIG. 10A is a view of the turbocharger of the assembly.

FIG. 10B is a sectional view of the turbocharger.

FIG. 11 is a perspective view of a third embodiment of the pump.

FIG. 12 is a perspective view of the pump of FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally speaking, FIG. 1 illustrates a wellsite system in which the inventive fracturing pump can be employed. The wellsite system of FIG. 1 may be onshore or offshore. In the wellsite system of FIG. 1, a borehole 11 may be formed in subsurface formations by rotary drilling using any suitable technique. A drill string 12 may be suspended within the borehole 11 and may have a bottom hole assembly 100 that includes a drill bit 105 at its lower end. A surface system of the wellsite system of FIG. 1 may include a platform and derrick assembly 10 positioned over the borehole 11, the platform and derrick assembly 10 including a rotary table 16, kelly 17, hook 18 and rotary swivel 19. The drill string 12 may be rotated by the rotary table 16, energized by any suitable means, which engages the kelly 17 at the upper end of the drill string 12. The drill string 12 may be suspended from the hook 18, attached to a traveling block (not shown), through the kelly 17 and the rotary swivel 19, which permits rotation of the drill string 12 relative to the hook 18. A top drive system could alternatively be used, which may be a top drive system well known to those of ordinary skill in the art.

In the wellsite system of FIG. 1, the surface system may also include drilling fluid 26 (also referred to as fracturing) stored in a pit/tank 27 at the wellsite. A pump 29 supported on a skid 28 may deliver the drilling fluid 26 to the interior of the drill string 12 via a port in the swivel 19, causing the drilling fluid to flow downwardly through the drill string 12 as indicated by the directional arrow 8. The drilling fluid 26 may exit the drill string 12 via ports in a drill bit 105, and circulate upwardly through the annulus region between the outside of the drill string 12 and the wall of the borehole 11, as indicated by the directional arrows 9. In this manner, the drilling fluid 26 lubricates the drill bit 105 and carries formation cuttings up to the surface, as the drilling fluid 26 is returned to the pit/tank 27 for recirculation. The drilling fluid 26 also serves to maintain hydrostatic pressure and prevent well collapse. The drilling fluid 26 may also be used for telemetry purposes. A bottom hole assembly 100 of the wellsite system of FIG. 1 may include logging-while-drilling (LWD) modules 120 and 120A and/or measuring-while-drilling (MWD) modules 130 and 130A, a roto-steerable system and motor 150, and the drill bit 105.

FIG. 2 shows a cutaway side view of a prior art fracturing pump, illustrating various components of the power assembly, the portion of the pump that converts rotational energy into reciprocating motion. A pump as shown in FIG. 2 could be used as pump 29 of FIG. 1, although many other fracturing pumps, including those with designs described below in accordance with certain embodiments of the present technique, could instead be used as pump 29. Pinion gears 52 along a pinion shaft 48 drive a larger gear referred to as a bull gear 42 (e.g., a helical gear or a herringbone gear), which rotates on a crankshaft 40. Pinion shaft 48 is turned by a motor (not shown). The crankshaft 40 turns to cause rotational motion of hubs 44 disposed on the crankshaft 40, each hub 44 being connected to or integrated with a connecting rod 46. By way of the connecting rods 46, the rotational motion of the crankshaft 40 (and hub 44 connected thereto) is converted into reciprocating motion. The connecting rods 46 couple to a crosshead 54 (a crosshead block and crosshead extension as shown may be referred to collectively as the crosshead 54 herein). The crosshead 54 moves translationally constrained by guide 57. Pony rods 60 connect the crosshead 54 to a piston 58. In the fluid end of the pump, each piston 58 reciprocates to move fracturing fluid in and out of valves in the fluid end of the pump 29.

Referring now to FIGS. 3-5, 11, and 12 two embodiments of the pump are shown. The first embodiment 100 is shown in FIGS. 3-5. The second embodiment 95 is shown in FIGS. 11 and 12. The embodiment 1000 shown in FIGS. 11 and 12 differs from the embodiment shown in FIGS. 3-5 in that pump 1000 is driven by a bull gear pinion drive arrangement. But the advantages are shared with the quintuplex pump 100 of FIG. 3. The pump 100 is gear box driven with gear ratio 6.963:1 (optional Gear Ratio: 7.842:1) to provide lower impact loading on crankshaft and stroke components for smooth drive operation. The pump 100 is equipped with largest 26″ to 27.5″ diameter crankshaft bearing design with larger roller bearing with closed shield to reduce roller contact loads and impact of shock loading.

It can be seen that the pump 100 has a crankshaft 102 driven by gears 103, which drives connecting rods 104, which ultimately causes reciprocating action of the pistons 106 to create pumping action as in the prior art model. Pump 100 and 1000 operate in essentially the same manner. Both pumps 100, 1000 have essentially identical frame and chassis construction. The pump 100 has an enhanced structural arrangement as can be seen especially in FIG. 4. It can be seen that the pump frame 110, which is used by pump 1000 also, has a series of partitioning structural enhancement members 112 which serve to reduce NVH and increase pump reliability. In a key aspect of the invention, NVH reduction greatly increases pump reliability by reducing stresses on the pump 100. The structural enhancement members 112 radiate outwardly from the opening 121 for the gears. The structural enhancement members 112 are formed also on dividing walls 123, radiating in the same pattern as those on end walls 125. The enhancement members 112 are basically elongated areas of reinforced metal. The dual chassis skid arrangement 114 is enhanced by adding multiple mounting points (for the pump 100 main body) for increased rigidity and to reduce deflection under load. In a key aspect of the invention, frame 110 and skid 114 are a single integrated structure, which greatly reduces noise, vibration, and harshness (NVH). The reduction in NVH enhances power output significantly. By increasing the size of key components such as the crossheads 116, and crankshaft 102 the pump 100 can handle greater loads. A closed loop oil feed system 118 (see especially FIG. 11) is part of an optimized lubrication system which reduces friction between crosshead 116 and crosshead guides 117. Low operating lube oil temperatures and high mechanical efficiency increase reliability. The size of the crankshaft bearing 131 can be made to vary between 26 and 27.6 inches, with the relatively large crankshaft bearing serving to reduce incidents of pump failure, and increase reliability and overall performance under heavy stress conditions. The roller bearing is situated in a closed shield 133 to reduce roller contact loads. It should also be noted that the enhanced frame 110 design discussed above also reduces stress on the oversized bearing. The use of only high performance metal grade enhances performance. The plunger size ranges from 2¾ inches to 6 inches.

A robust sealing system is provided to improve leak and thermal stresses handling during harsh high temperature Frac operation in the field. As previously stated, the interior components of the pump, including the plunger 139, can be interchangeably replaced to increase power output, a key aspect of the invention. In a preferred embodiment power generation ranges from 3000 HP to 4500 HP by way of interchangeable components. Also, the pump allows variable high pressure output and high flow rate based on variance of plunger size and stroke length. Specifically, an 8 inch stroke creates a horsepower of about 3300 HP, with 9, 10, and 11 inch strokes creating 3700 HP, 4000 HP, and 4500 HP, respectively.

Crosshead 116 is designed to improve friction issues and reduce wear and noise and integrate with a two piece crosshead head as an alternative design. Innovation to integrate closed loop fluid system to increase stroke component life and improve lubrication, reduce contamination by utilizing fluid mechanics and thermodynamics and machine design innovation applied to the fluid end design to increase life cycle, durability.

The fluid end 122 is equipped with a 45 degree valve seat—(With offset angle valve) to increase flow pressure and reduce. Adding fluid channels allows for better lubrication of components distribution, and reduces thermal stress. Finally, a new sealing design using fluid mechanics applications to eliminate leak and increase sealing life.

FIGS. 7 and 8 show the closed loop lubrication system 140. The purpose of the closed loop oil lubrication system is to provide cooling to the stroke components, increase the life of the stroke components such as the crosshead 116, connector rod bearing and crankshaft bearing 131. Efficient lubrication and reduced contamination will increase durability and life of the stroke components. More efficient lubrication circulation and effective contamination reduction will immediately reduce overheating and reduce failure.

The flow diagram shown in FIG. 11 circulates oil or lubricant to stroke components and crankshaft bearing 131 of the pump 100. The oil loop lines circulate from the oil tank with action of the feed pump 198. Flow regulation is accomplished with check valves 9, relief valve 7, and filters 5, and 6 to eliminate contamination. A solenoid (not shown) is to improve and regulate steady pressure to the stroke components as shown in the diagram. Oil recirculated from the pump 100 is cooled by a heat exchanger 200 before being recirculated via tank or reservoir 4.

As is known in the art, a fracturing pumps chamber will experience crosshead shock when the lifting forces acting on the crosshead exceed the weight of the crosshead assembly. The present invention increases power output system by minimizing the slight crosshead shock and attendant pressure surges in the suction manifold during the suction stroke. A slight crosshead shock always occurs at the beginning of the suction stroke when the connecting rod firsts drops below the center line and the discharge valve 7 is still open to the high fluid pressure resulting in a lifting force. A low level shock is observed with both pump manifolds at low pump speeds. At higher pump speeds, acceleration head loss increases creating high surge pressures later in the suction stroke. To reduce high crosshead shock is to reduce the thermal expansion of the crosshead guide and effectively increase bearing surface area to reduce heat and increase lubrication.

The measured shock load is defined as the lifting force by multiplying the fluid peak pressure times the piston area when the force is large enough to lift the crosshead assembly. When crosshead shock occurs, all the pump drive components also have an instantaneous reversal of loads going from tension to compression. This reversal adds shock loads to all the bearings.

Using the inventive assembly 100, 1000 reduced the average crosshead shock by a factor of 2.4 to 4.8 at higher pump speeds. In a key aspect of the invention, a precision throttling valve 215 on the suction piping 217, or equivalent speed control on the centrifugal pump motor 198 is used to adjust suction feed pressures.

The pump 100, 1000 output may be enhanced via turbocharger 219. The turbocharger 219, like its generational predecessors recovers hydraulic energy from the high pressure concentrate and transfers that energy to a feed. This system 100, 1000 is using a turbo rotor 221 to increase the pressure concentration (pressure booster). This turbocharging system can be used for reverse osmosis process for the feed stream.

Referring now to FIGS. 11-12 pump 1000 is shown. It can be seen that the pump 1000 is similar to the pump of FIG. 3, the only difference being the use of a bull gear pinion drive arrangement. The pump 1000 has a crankshaft 1002, which drives connecting rods 104, which ultimately cause reciprocating action of the pistons 1006 to create pumping action as in the prior art model. In a key aspect of the invention, the crankshaft 1002 is connected to connecting rods vis a bull gear pinion drive arrangement. The pump 1000 has an enhanced structural arrangement as can be seen especially in FIG. 16. It can be seen that the pump frame 1010 has a series of partitioning structural enhancement members 1012 which serve to reduce NVH and increase pump reliability. The dual chassis skid arrangement 1014 is enhanced by adding multiple mounting points for increased rigidity and to reduce deflection under load as in the pump 100. By increasing the size of key components such as the crossheads 1016, and crankshaft 1002 the pump 1000 can handle greater loads. The closed loop oil feed system (FIG. 11) is part of an optimized lubrication system which reduces friction between crosshead 1016 and crosshead guides 1017. Low operating lube oil temperatures and high mechanical efficiency increase reliability.

A robust sealing system is provided to improve leak and thermal stresses handling during harsh high temperature Frac operation in the field. As previously stated, the interior components of the pump 100, including the plunger 139, can be interchangeably replaced to increase power output, a key aspect of the invention. Stroke length can be varied between 8 and 11 inches, with corresponding variances in output power. In a preferred embodiment power generation ranges from 3000 HP to 4150 HP. Also, the pump allows high pressure output and high flow rate based on variance of plunger size.

The Pump 1000 is Bull Gear and pinion Drive with Gear Ratio 6.353. The frac pump 1000 is engineered to produce high horsepower, high pressure and flow rates, even at low operating speeds, which reduces stress and wear to components. The use of various long stroke design as described above reduces the number of load reversal in critical components and increases the life of fluid end parts. The pump 1000 is designed for continuous-duty pressure pumping operations at a sustained 277,000-2800,000 pound rod load, 24 hours per day, per full week.

It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims: 

I claim:
 1. A fracturing pump assembly comprising: a frame having a plurality of bores formed therethrough; and a plurality of crossheads disposed in the plurality of bores, respectively, and adapted to reciprocate therein; a skid on which a power end is mounted; whereby said frame is reinforced by partition and said skid is integrated into said frame.
 2. The pump of claim 1 wherein said frame includes opposing end walls with a series of partitioning walls disposed therebetween, all of said walls having an opening formed therein, where said walls have a series of enhancement members radiating outwardly therefrom.
 3. A fracturing pump assembly comprising: a frame having a plurality of bores formed therethrough; and a plurality of crossheads disposed in the plurality of bores, respectively, and adapted to reciprocate therein; a set of gears disposed within said frame, said gears mechanically connected to a source of motive power for turning a crankshaft, said crankshaft operating to cause reciprocating motion of a series of plungers having a predetermined stroke length a skid on which a power end is mounted; whereby said frame is reinforced by partition and said skid is integrated into said frame. 